1. Field of the Invention
The present invention relates to electric or electronic animal traps, and relates more particularly to an animal trap adapted to catch and electrocute a targeted animal, and also to rearm in the event the continuing presence of the animal is not detected upon completion of a killing cycle.
Although the concepts of the instant invention are equally applicable to traps for animals of any size, devices of this type are primarily utilized in connection with the trapping and killing of rats and the description will, therefore, focus on this application.
2. Description of the Related Art
A number of animal traps have been developed which include structural devices to trap an animal and prevent its escape, along with electric or electronic components which act to kill the trapped animal.
One such device is found in U.S. Pat. No. 6,609,328 (“the '328 patent”, which is hereby expressly incorporated herein by reference as if fully set forth in its entirety. The trap disclosed in the '326 patent electrocutes the animal while also providing a visual indicator signaling when the trap has initiated a kill cycle and thereafter requires servicing to remove an electrocuted animal.
Other trap designs that have relied upon electrocution and effectively prevented pest-escape in the prior art are set forth in U.S. Pat. No. 6,735,899 (“the '899 patent”), which is hereby expressly incorporated herein by reference as if fully set forth in its entirety. The electronic traps disclosed in the '899 patent utilize at least two fixed barriers or diverter members that are positioned between the opening of the trap and a pair of spaced charge plates electrically connected to a voltage source. The barriers reduce the risk of escape so that, when the trap enters the standby mode after trap activation through contact of the pest with the pair of plates, the trap is more likely to have been effective in killing and retaining the dead pest.
Even with the structures intended to prevent escape, larger vermin such as rats may not have been killed and may have escaped. As a result, since the standby mode indicates the presence of a dead pest, because it was in fact initiated by a false trigger, wasted effort is expended by exterminator personnel or other users in servicing and resetting a trap which is, in fact, already empty.
Hence, a trap having three killing plates for greater killing power has been developed as described in U.S. Pat. No. 7,219,466 (“the '466 patent”), also assigned to the present assignee. The disclosure of the '466 patent is also hereby expressly incorporated by reference as if fully set forth herein in its entirety. The trap disclosed in the '466 patent application electrocutes the animal by activating a pair of spaced killing plates, with the first plate being electrically coupled to a third plate that is brought to the voltage level of the first plate approximately 1 msec after circuit activation. The killing circuit is activated when a pest of known impedance is sensed across the pair of plates. The use of three plates both increases electrocution capability and decreases the likelihood of pest escape once the trap has been activated.
The trap of the '466 patent also uses the sensing of a known impedance across the pair of plates after the killing cycle to determine whether the pest is still present and, in the absence thereof, automatically rearms itself without requiring human intervention. If a dead rat is present, however, the trap enters the standby mode and provides a visual indicator that trap servicing is required.
Because the '466 patent relies upon detecting impedance across the plates within a range which is representative of a rat, the trap may not detect undesired pests which fall outside this range. Further, if the rat is present but is not in contact with both plates, as when the animal sits up on its haunches to investigate the roof area of the trap, its presence will not be detected. Since detection of a resistance value across the plates is also used after trap activation to determine whether or not to automatically reset, should there be any failure to detect a killed rodent due to the rat's positioning after death, i.e., the rat's body is not in solid contact with one of the plates, the trap would nonetheless reset. This would be undesirable because rats are known to avoid other dead rats so that the trap would be ineffective in capturing a second rat. In addition, the trap could “hide” the dead carcass for an extended period, exposing the surrounding area to the resulting decay and bacteria growth, since the trap would not provide the visual indicator that a dead animal is contained therein and trap service is required.
Therefore, a need exists for a trap that combines an electronic circuit having high voltage to provide killing power effective to terminate rats, with a detection mechanism that is able to detect the presence of any pest. Preferably, the trap will also rearm the trap without human intervention in the event of pest escape.